The frozen food company reiterated its apology as the FSA ordered firms to carry out tests on all processed beef foods.

Mr Paterson said investigations into how beef products had been contaminated with horse meat were ongoing but "the evidence so far suggests ... it's either criminal activity or gross negligence".

Tesco, Aldi and Findus have all had to withdraw food products.

It also emerged on Friday that food served in schools and hospitals may contain horse meat.

The police were drawn into the scandal on Friday amid fears that criminals may be involved in supplying horse meat labelled as beef. The development followed confirmation that some Findus beef lasagnes were made entirely of horse meat.